Blood oximeter

• US 5,596,986 A
• Filed: 02/16/1993
• Issued: 01/28/1997
• Est. Priority Date: 03/17/1989
• Status: Expired due to Fees

• Current Assignee: Scico Incorporated
• Original Assignee: Scico Incorporated
• Inventors: Goldfarb, David
• Primary Examiner(s): Shay, David M.
• Application Number:
  US08/018,349
• Time in Patent Office: 1,442 Days
• Field of Search: 128/633, 128/634, 128/637, 606/2, 606/3, 356/39-41, 356/364, 356/367, 607/88, 607/89
• US Class Current: 600/323
• CPC Class Codes: A61B 5/14551 for measuring blood gases
• CPC Class Codes: A61B 5/14552 Details of sensors specially adapted therefor
• CPC Class Codes: A61B 5/1459 invasive, e.g. introduced into the body by a catheter A61B5/1464 takes precedence
• CPC Class Codes: A61B 5/411 Detecting or monitoring allergy or intolerance reactions to an allergenic agent or substance
• CPC Class Codes: G01N 21/314 with comparison of measurements at specific and non-specific wavelengths dual wavelength spectrometry G01J3/427
• CPC Class Codes: G01N 21/49 within a body or fluid

Abstract

A backscatter type non-invasive blood oximeter utilizes a coherent, polarized and tuneable monochromatic light source to measure parameters related to blood oxygen content. A microprocessor calculates information related to blood oxygen content from the sensed information and a display system displays the blood oxygen content.

Claims

1. An apparatus for measuring the oxygen content of blood within a patient comprising:

a light source for transmitting an incident beam with a linearly polarized, monochromatic light having a first amplitude;

a directional coupler having a first port, a second port, and a third port, said second port optically coupled to said light source;

an optical fiber coupled to the third port of said directional coupler;

an optical coupler coupled to said optical fiber for interfacing between said optical fiber and said patient, with said optical coupler including a flat optical glass for flattening an underlying capillary bed of skin of said patient, thereby presenting a flat surface area perpendicular to said optical fiber, with the incident beam passing through the second port and the third port of said directional coupler, through said optical fiber and said optical coupler, to the underlying capillary bed, with a portion of the incident beam reflecting from the underlying capillary bed as a reflected beam, with the reflected beam passing from said optical coupler, through the optical fiber, through the third port and out the first port of said directional coupler;

a polarizing filter coupled to said first port for filtering the reflected beam with linear polarization and for passing the reflected beam having a 180 degree phase shift with respect to the incident beam;

a detector optically coupled through said polarizing filter to the first port of said directional coupler for measuring a second amplitude of the reflected beam having a 180 degree phase shift with respect to the incident beam, with the reflected beam passing from said underlying capillary bed through the optical coupler, through the third port of said directional coupler, through the first port of said directional coupler, and through said polarizing filter; and

processing means, electrically coupled to said light source and to said detector, for receiving the first amplitude from the light source and the second amplitude from the detector, said processing means having a data table summarizing blood oxygen values and comparing the first amplitude with the second amplitude and, referencing the data table, determining a value indicating a quantity of oxygen in the blood.

2. An apparatus for spectrophotometrically measuring and displaying an oxygen content of blood within a living patient comprising:

a tuneable laser source for generating a plurality of light signals as an incident beam having a measured intensity, each of said plurality of light signals being coherent, linearly polarized and monochromatic;

a directional coupler having a first port, a second port and a third port, said first port optically connected to a polarizing filter and a detector, said second port optically conected to said tuneable laser source, and said third port optically connected through an optical fiber to the patient;

means coupled to the optical fiber and adapted for directing the incident beam through the optical fiber into the patient, non-invasively and transcutaneously along a path, with the optical fiber perpendicular to an underlying capillary bed of skin of the patient;

means coupled to the optical fiber and adapted for directing backscattered radiation generated within the patient in response to said incident beam along said path as a reflected beam to said first port, said polarizing filter and said detector;

said polarizing filter for filtering the reflected beam with linear polarization and for passing the reflected beam having a 180 degree phase shift with respect to the incident beam as a 180-degree-phase-shifted-reflected beam;

said detector adapted to measure an intensity of the 180-degree-phase-shifted-reflected beam; and

calculating means, electrically coupled to the detector and to the tuneable laser source, having a data table summarizing blood oxygen values and responsive to receiving and comparing the measured intensity of the incident beam and the intensity of the 180-degree-phase-shifted-reflected beam, for determining and displaying the oxygen content of blood.

3. The apparatus of claim 2 with said different wavelengths are in the range of plurality of light signals being in a range from 600 to 1000 nanometers.

4. The apparatus of claim 2 with said tuneable laser source consisting essentially of a single tuneable laser generating said plurality of light signals sequentially.

5. The apparatus of claim 4 including means for sweeping said plurality of light signals every 30 microseconds.

6. The apparatus of claim 2 with said detector including a PIN diode.

7. The apparatus of claim 6 with said tuneable laser source consisting essentially of a single tuneable laser generating said plurality of light signals sequentially.

8. The apparatus of claim 7 including means for sweeping said plurality of light signals every 30 microseconds.

9. An apparatus for spectrophotometrically measuring and displaying information related to a quantity present of a preselected constituent of a living patient'"'"'s blood comprising:

a solid state laser tuneable in the range of about 600 nm-1000 nm for generating a plurality of light signals as an incident beam, each of said plurality of light signals being coherent, linearly polarized and monochromatic;

a directional coupler having a first port, a second port, and a third port, said first port optically coupled to a linear polarizing filter oriented 180°

out of phase with polarization of said incident beam, said first port also optically coupled to a PIN diode detector, said second port optically coupled to said laser, and said third port optically coupled through an optical fiber to the patient;

means coupled to the optical fiber and adapted for directing said incident beam along a path through the optical fiber into the patient, non-invasively and transcutaneously, with the optical fiber perpendicular to an underlying capillary bed of skin of the patient;

means coupled to the optical fiber and adapted for directing backscattered radiation, generated within the patient in response to said incident beam, back along said path as a reflected beam to said first port, said linear polarizing filter and said PIN diode detector;

said linear polarizing filter for filtering the reflected beam with linear polarization and for passing the reflected beam having a 180 degree phase shift with respect to the incident beam as a 180-degree-phase-shifted-reflected beam;

said PIN diode detector adapted to measure an intensity of said 180-degree-phase-shifted-reflected beam; and

calculation means, electrically coupled to said laser and to said PIN diode detector, for receiving and comparing an intensity of the incident beam and the intensity of the 180-degree-phase-shifted-reflected beam, said calculation means having a plurality of data tables summarizing quantities of a plurality of constituents of blood, respectively, said calculation means for referencing a particular data table summarizing the preselected constituent and for determining and displaying, using the intensity of the incident beam and the intensity of the 180-degree-phase-shifted-reflected beam, a value indicating a quantity of the preselected constituent in the blood.

10. The apparatus of claim 9 including means for sweeping said plurality of light signals every 30 microseconds.

11. The apparatus of claim 9 with said solid state laser including means for generating said plurality of light signals sequentially.

12. A spectrophotometric method for transcutaneously and non-invasively determining an oxygen content of blood within a living patient, using a tunable laser source capable of producing monochromatic light at a multiplicity of frequencies, a directional coupler, a polarizing filter, a detector, an optical fiber, an optical coupler, and a processor, the method comprising the steps of:

generating, using the tunable laser source, a plurality of light signals having wavelengths within the range of about 600 nm to about 1000 nm as an incident beam, each of said plurality of light signals being coherent, linearly polarized and monochromatic;

applying said incident beam to the directional coupler, the directional coupler having a first port, second port and a third port, said first port optically coupled to the linear polarizing filter oriented 180°

out of phase with the polarization of said plurality of light signals, said first port of said directional coupler also coupled to the detector, said second port optically coupled to said tunable laser source, and said third port optically coupled, through the optical fiber and the optical coupler, to the patient;

directing the incident beam into the patient non-invasively and transcutaneously along an optical path;

directing backscattered radiation, generated within the patient in response to said incident beam, as a reflected beam back along said optical path to said third port, through said first port, and to said linear polarizing filter;

filtering, by said polarizing filter, said reflected beam and passing a portion of the reflected beam having a 180 degree phase shift with respect to said incident beam to said detector as a 180-degree-phase-shifted-reflected beam;

measuring, by the detector, an intensity of said 180-degree-phase-shifted-reflected beam;

comparing, by the processor, an intensity of said incident beam and the measured intensity of said 180-degree-phase-shifted-reflected beam;

referencing, by the processor, a data look up table summarizing blood oxygen values;

calculating, using the comparison and the reference, an oxygen content of blood; and

displaying the oxygen content of blood.

13. A spectrophotometric method for transcutaneously and non-invasively determining an oxygen content of blood within a living patient, using a tunable laser source capable of producing monochromatic light at a multiplicity of frequencies;

a directional coupler, optically coupled to said tunable laser source, having a first port, a second port and a third port;

a polarizing filter, optically coupled to said first port;

a detector, optically coupled to said first port;

an optical fiber, optically coupled to said third port;

an optical coupler, optically coupled to said optical fiber and perpendicular to said optical fiber; and

a processor, electrically coupled to said tunable laser source and to said detector, the method comprising the steps of;

generating, with said tunable laser source, a plurality of light signals as an incident beam in the range of 600 nm-1000 nm, each of said plurality of light signals being coherent, polarized and monochromatic;

transmitting a first amplitude of said incident beam to said processor;

applying said incident beam to the second port of said directional coupler;

optically conveying said incident beam out the third port of said directional coupler, through said optical fiber, to said optical coupler;

directing the incident beam into the patient non-invasively and transcutaneously along a path;

directing backscattered radiation, generated within the patient in response to said incident beam, along said path as a reflected beam to said third port and out said first port;

filtering with linear polarization, by said polarizing filter, said reflected beam and passing a portion of the reflected beam having a 180 degree phase shift with respect to said incident beam as a 180-degree-phase-shifted-reflected beam;

detecting, by said detector, the 180-degree-phase-shifted-reflected beam;

measuring a second amplitude of the 180-degree-phase-shifted-reflected beam;

transmitting the second amplitude to said processor;

comparing, by said processor, the first amplitude and the second amplitude;

referencing, by said processor, a data look up table;

calculating, using the comparison of the first amplitude and the second amplitude, and the data look up table, an oxygen content of blood; and

displaying the oxygen content of blood.

14. The method of claim 13 further comprising the step of sweeping said plurality of light signals every 30 microseconds.